PoducateMe: Practical Solutions for Podcasting in Education
40
Printable copies of the guide are available for purchase and immediate download at
Bass frequency attenuation also helps combat “proximity effect,” which is an
exaggeration of low-frequency sounds by a microphone when it is placed close to an
instrument or vocalist. This effect can begin when the sound source is about two feet
away and becomes more noticeable as the source gets closer to the microphone.
Some professional microphones, such as the Shure KSM27 ($299.95), feature a
switch that allows the user to add low-frequency filtration on an as-needed basis.
The Frequency Response Curve
The frequency response curve is often included in microphone specs and offers one
of the most valuable tools to help predict how a mic will sound. The curves are not
always spot-on accurate, but they’re intended to reveal a microphone’s ability to
capture certain portions of the audible spectrum. Figure 10 depicts the response
curve for the Shure KSM27. The x axis shows frequency in Hertz, while the y axis
shows response in decibels (db).
Figure 10: Frequency response curve for the Shure KSM27.
Note how the mic has been “tailored” for vocals, as described earlier. The curve
reveals a lift at around 3-4kHz that tops out between 6 and 7kHz. In addition, a mild
bass boost at around 50Hz is introduced for added warmth.
Figure 11 demonstrates the mic’s frequency response with the microphone’s low
frequency roll-off and cut-off filters applied.
